diff --git a/src/main/java/ch/progetto152/controller/LocationController.java b/src/main/java/ch/progetto152/controller/LocationController.java
index 7a2cdfb..fd56a15 100644
--- a/src/main/java/ch/progetto152/controller/LocationController.java
+++ b/src/main/java/ch/progetto152/controller/LocationController.java
@@ -12,6 +12,8 @@ import java.util.List;
 @RestController
 @RequestMapping("/progetto152/location")
 public class LocationController {
+
+    // Inject the LocationService
     private final LocationService locationService;
 
     @Autowired
@@ -19,12 +21,14 @@ public class LocationController {
         this.locationService = locationService;
     }
 
+    // Handle GET request to get all locations
     @GetMapping("")
     public ResponseEntity<List<LocationEntity>> getAllLocations() {
         List<LocationEntity> Locations = locationService.getAllLocations();
         return new ResponseEntity<>(Locations, HttpStatus.OK);
     }
 
+    // Handle GET request to get a specific location by name
     @GetMapping("/{name}")
     public ResponseEntity<LocationEntity> getLocationByName(@PathVariable("name") String name) {
         LocationEntity location = locationService.getLocationByName(name);
@@ -35,15 +39,17 @@ public class LocationController {
         }
     }
 
+    // Handle POST request to create a new location
     @PostMapping("")
     public ResponseEntity<LocationEntity> createLocation(@RequestBody LocationEntity location) {
         LocationEntity createdLocation = locationService.createLocation(location);
-        if(createdLocation == null) {
+        if (createdLocation == null) {
             return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
         }
         return new ResponseEntity<>(createdLocation, HttpStatus.CREATED);
     }
 
+    // Handle PUT request to update an existing location
     @PutMapping("/{name}")
     public ResponseEntity<LocationEntity> updateLocation(@PathVariable("name") String name, @RequestBody LocationEntity location) {
         LocationEntity location1 = locationService.updateLocation(name, location);
@@ -54,6 +60,7 @@ public class LocationController {
         }
     }
 
+    // Handle DELETE request to delete an existing location by name
     @DeleteMapping("/{name}")
     public ResponseEntity<Void> deleteLocation(@PathVariable("name") String name) {
         boolean deleted = locationService.deleteLocation(name);
diff --git a/src/main/java/ch/progetto152/controller/UserController.java b/src/main/java/ch/progetto152/controller/UserController.java
index 1dabf64..f0f6f6a 100644
--- a/src/main/java/ch/progetto152/controller/UserController.java
+++ b/src/main/java/ch/progetto152/controller/UserController.java
@@ -14,6 +14,8 @@ import java.util.List;
 @RequestMapping("/progetto152/user")
 public class UserController {
 
+
+    // Inject the UserService
     private final UserService userService;
 
     @Autowired
@@ -21,12 +23,14 @@ public class UserController {
         this.userService = userService;
     }
 
+    // Handle GET request to get all users
     @GetMapping("")
     public ResponseEntity<List<UserEntity>> getAllUsers() {
         List<UserEntity> users = userService.getAllUsers();
         return new ResponseEntity<>(users, HttpStatus.OK);
     }
 
+    // Handle GET request to get user by id
     @GetMapping("/id/{id}")
     public ResponseEntity<UserEntity> getUserById(@PathVariable("id") Long id) {
         UserEntity user = userService.getUserById(id);
@@ -37,6 +41,7 @@ public class UserController {
         }
     }
 
+    // Handle GET request to get user by username
     @GetMapping("/{username}")
     public ResponseEntity<UserEntity> getUserByUsername(@PathVariable("username") String username) {
         UserEntity user = userService.getUserByUsername(username);
@@ -47,16 +52,18 @@ public class UserController {
         }
     }
 
+    // Handle POST request to create a new user
     @PostMapping("")
     public ResponseEntity<UserEntity> createUser(@RequestBody UserEntity user) {
         UserEntity createdUser = userService.createUser(user);
-        if(createdUser == null) {
+        if (createdUser == null) {
             return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
         }
         createdUser.setAdmin(0);
         return new ResponseEntity<>(createdUser, HttpStatus.CREATED);
     }
 
+    // Handle PUT request to update an existing user
     @PutMapping("/{id}")
     public ResponseEntity<UserEntity> updateUser(@PathVariable("id") Long id, @RequestBody UserEntity user) {
         UserEntity updatedUser = userService.updateUser(id, user);
@@ -67,6 +74,7 @@ public class UserController {
         }
     }
 
+    // Handle DELETE request to delete an existing user
     @DeleteMapping("/{id}")
     public ResponseEntity<Void> deleteUser(@PathVariable("id") Long id) {
         boolean deleted = userService.deleteUser(id);
diff --git a/src/main/java/ch/progetto152/controller/WaypointController.java b/src/main/java/ch/progetto152/controller/WaypointController.java
index 527205a..e4df318 100644
--- a/src/main/java/ch/progetto152/controller/WaypointController.java
+++ b/src/main/java/ch/progetto152/controller/WaypointController.java
@@ -12,6 +12,8 @@ import java.util.List;
 @RestController
 @RequestMapping("/progetto152/waypoint")
 public class WaypointController {
+
+    // Iject the WaypointService instance
     private final WaypointService waypointService;
 
     @Autowired
@@ -19,12 +21,14 @@ public class WaypointController {
         this.waypointService = waypointService;
     }
 
+    // Handle the GET request to get all waypoints
     @GetMapping("")
     public ResponseEntity<List<WaypointsEntity>> getAllWaypoints() {
         List<WaypointsEntity> waypoint = waypointService.getAllWaypoints();
         return new ResponseEntity<>(waypoint, HttpStatus.OK);
     }
 
+    // Handle the GET request to get all waypoints by location
     @GetMapping("/{location}")
     public ResponseEntity<List<WaypointsEntity>> getAllWaypoints(@PathVariable("location") String location) {
         System.out.println(waypointService.getAllWaypointsByLocation(location));
@@ -32,6 +36,8 @@ public class WaypointController {
         return new ResponseEntity<>(waypoint, HttpStatus.OK);
     }
 
+
+    // Handle the GET request to get a specific waypoint by id
     @GetMapping("/{location}/{id}")
     public ResponseEntity<WaypointsEntity> getWaypoint(@PathVariable("location") String location, @PathVariable("id") Long id) {
         WaypointsEntity waypoint = waypointService.getWaypointById(id);
@@ -46,6 +52,7 @@ public class WaypointController {
         }
     }
 
+    // Handle the GET request to get a specific waypoint by id
     @GetMapping("/id/{id}")
     public ResponseEntity<WaypointsEntity> getWaypointById(@PathVariable("id") Long id) {
         WaypointsEntity waypoint = waypointService.getWaypointById(id);
@@ -56,6 +63,7 @@ public class WaypointController {
         }
     }
 
+    // Handle the POST request to create a new waypoint
     @PostMapping("")
     public ResponseEntity<WaypointsEntity> createWaypoint(@RequestBody WaypointsEntity waypoint) {
         WaypointsEntity createdWaypoint = waypointService.createWaypoint(waypoint);
@@ -65,6 +73,7 @@ public class WaypointController {
         return new ResponseEntity<>(createdWaypoint, HttpStatus.CREATED);
     }
 
+    // Handle the PUT request to update an existing waypoint
     @PutMapping("/{id}")
     public ResponseEntity<WaypointsEntity> updateWaypoint(@PathVariable("id") Long id, @RequestBody WaypointsEntity waypoint) {
         WaypointsEntity updatedWaypoint = waypointService.updateWaypoint(id, waypoint);
@@ -75,6 +84,7 @@ public class WaypointController {
         }
     }
 
+    // Handle the DELETE request to delete an existing waypoint
     @DeleteMapping("/{id}")
     public ResponseEntity<Void> deleteWaypoint(@PathVariable("id") Long id) {
         boolean deleted = waypointService.deleteWaypoint(id);
diff --git a/src/main/java/ch/progetto152/controller/WaypointVisitedController.java b/src/main/java/ch/progetto152/controller/WaypointVisitedController.java
index b4358bb..a048979 100644
--- a/src/main/java/ch/progetto152/controller/WaypointVisitedController.java
+++ b/src/main/java/ch/progetto152/controller/WaypointVisitedController.java
@@ -14,6 +14,8 @@ import java.util.List;
 @RestController
 @RequestMapping("/progetto152/waypoint/visited")
 public class WaypointVisitedController {
+
+    // Iject the WaypointVisitedService and UserService
     private final WaypointVisitedService waypointVisitedService;
 
     private final UserService userService;
@@ -24,14 +26,14 @@ public class WaypointVisitedController {
         this.userService = userService;
     }
 
+    // Handle GET request to get all waypoints visited
     @GetMapping("")
     public ResponseEntity<List<WaypointsVisitedEntity>> getAllWaypointsVisited() {
         List<WaypointsVisitedEntity> waypointVisited = waypointVisitedService.getAllWaypointsVisited();
         return new ResponseEntity<>(waypointVisited, HttpStatus.OK);
     }
 
-
-
+    // Handle GET request to get all waypoints visited by user
     @GetMapping("/{id}")
     public ResponseEntity<WaypointsVisitedEntity> getWaypointVisitedByWaypointId(@PathVariable("id") Long id) {
         WaypointsVisitedEntity waypointVisited = waypointVisitedService.getWaypointsVisitedByWaypointId(id);
@@ -42,6 +44,7 @@ public class WaypointVisitedController {
         }
     }
 
+    // Handle GET request to get all waypoints visited by user
     @GetMapping("/{user}/{id}")
     public ResponseEntity<Boolean> getWaypointVisitedByWaypointIdAndUserId(@PathVariable("user") String username, @PathVariable("id") Long waypointId) {
         UserEntity user = userService.getUserByUsername(username);
@@ -55,6 +58,7 @@ public class WaypointVisitedController {
         }
     }
 
+    // Handle GET request to get all waypoints visited by user
     @GetMapping("/user/{id}")
     public ResponseEntity<WaypointsVisitedEntity> getWaypointVisitedByUserId(@PathVariable("id") Long id) {
         WaypointsVisitedEntity waypointVisited = waypointVisitedService.getWaypointsVisitedByUserId(id);
@@ -65,6 +69,7 @@ public class WaypointVisitedController {
         }
     }
 
+    // Handle POST request to create a new waypoint visited
     @PostMapping("")
     public ResponseEntity<WaypointsVisitedEntity> createWaypointVisited(@RequestBody WaypointsVisitedEntity waypointVisited) {
         WaypointsVisitedEntity createdWaypoint = waypointVisitedService.createWaypoint(waypointVisited);
@@ -74,6 +79,7 @@ public class WaypointVisitedController {
         return new ResponseEntity<>(createdWaypoint, HttpStatus.CREATED);
     }
 
+    // Handle PUT request to update a waypoint visited
     @PutMapping("/{id}")
     public ResponseEntity<WaypointsVisitedEntity> updateWaypointVisited(@PathVariable("id") Long id, @RequestBody WaypointsVisitedEntity waypointVisited) {
         WaypointsVisitedEntity updatedWaypoint = waypointVisitedService.updateWaypoint(id, waypointVisited);
@@ -84,6 +90,7 @@ public class WaypointVisitedController {
         }
     }
 
+    // Handle DELETE request to delete a waypoint visited
     @DeleteMapping("/{id}")
     public ResponseEntity<Void> deleteWaypointVisited(@PathVariable("id") Long id) {
         boolean deleted = waypointVisitedService.deleteWaypoint(id);
diff --git a/src/main/java/ch/progetto152/services/LocationService.java b/src/main/java/ch/progetto152/services/LocationService.java
index 8b02b0b..53d4613 100644
--- a/src/main/java/ch/progetto152/services/LocationService.java
+++ b/src/main/java/ch/progetto152/services/LocationService.java
@@ -11,7 +11,7 @@ import java.util.List;
 @Service
 public class LocationService {
 
-    private ErrorChecking errorChecking = new ErrorChecking();
+    private final ErrorChecking errorChecking = new ErrorChecking();
     private final LocationRepository locationRepository;
 
     @Autowired
diff --git a/src/main/java/ch/progetto152/services/WaypointVisitedService.java b/src/main/java/ch/progetto152/services/WaypointVisitedService.java
index 35f0dc7..0a85d41 100644
--- a/src/main/java/ch/progetto152/services/WaypointVisitedService.java
+++ b/src/main/java/ch/progetto152/services/WaypointVisitedService.java
@@ -1,6 +1,5 @@
 package ch.progetto152.services;
 
-import ch.progetto152.entity.UserEntity;
 import ch.progetto152.entity.WaypointsVisitedEntity;
 import ch.progetto152.repository.WaypointVisitedRepository;
 import ch.progetto152.utility.ErrorChecking;
@@ -63,13 +62,8 @@ public class WaypointVisitedService {
         return true;
     }
 
-
     public Boolean getWaypointsVisitedByWaypointIdAndUserId(Long waypointId, Long userId) {
         WaypointsVisitedEntity waypointsVisited =  waypointVisitedRepository.findWaypointsVisitedEntitiesByUserIdAndWaypointId(userId, waypointId).orElse(null);
-        if (waypointsVisited != null) {
-            return true;
-        } else {
-            return false;
-        }
+        return waypointsVisited != null;
     }
 }
diff --git a/src/main/java/ch/progetto152/utility/ErrorChecking.java b/src/main/java/ch/progetto152/utility/ErrorChecking.java
index 1993d19..cd8ce2f 100644
--- a/src/main/java/ch/progetto152/utility/ErrorChecking.java
+++ b/src/main/java/ch/progetto152/utility/ErrorChecking.java
@@ -6,6 +6,8 @@ import ch.progetto152.entity.UserEntity;
 import ch.progetto152.entity.WaypointsEntity;
 import ch.progetto152.entity.WaypointsVisitedEntity;
 
+
+// This class is used to check if the data received from the client is valid
 public class ErrorChecking {
 
     public boolean checkUser(UserEntity user){